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7652 Views 47 Replies 10 Participants Last post by  Randall-in-Mpls
Anyone in the Twin Cities have a portable torch kit, and interested in playing "Straighten-a-Frame?" I've got the vise and the levers. I just need a fire source.

This is the victim:

The right tube (left in the picture above) of the triple spine is bent, and the head tube twisted.

I believe that if we apply heat and leverage in the right places, the spine tube can be straightened, causing the head tube to untwist. I had resigned myself to leaving this for Spring, but after recently acquiring a front end, I'm eager to make some progress.

Any takers? If others want to help, too, we'll order a pizza and make a party of it.

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That top picture makes it look like it needs a good pull to the left but pictures also lie.
The center tube is straight, as far as I can tell. Because of the twist, the bracket at the bottom of the head tube is displaced to the right (left in the photo.)

Have it pressed? In a machine shop on a hydraulic press. The heat would expand the tube I think to much.

I have had front forks done that way,cold. The metal is stretched and by pressing cold that may align the front and the back of the frame by compressing.

I'd be very hesitant to try to straighten it cold for fear of causing cracks in the welds. You can cold press a fork tube because there are no welds. And even if the right tube ends up a little longer, it can retain a little dip, as long as the head tube it straight. I doubt it will be noticeably different.

Nice looking stator! Mine on the 81 was very dark epoxy. The one in my 81 now looks like yours.

I haven't applied a meter to it yet, so I don't know the actual condition. When this project reaches final assembly, I might mount a higher-outpur Goldwing stator, and put this one in my Ignitech-sparked CX.

Why not get a new frame? Simpler and you don't have to worry about it being a little "off".
First, I'm too cheap to throw something out if I can make it work.

Second, it's hard to find just a frame, and I don't have the space for yet another parts bike. Oh, and I'm cheap.

Third, it will be an interesting challenge. And did I mention, I'm cheap?

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Doh! The stuttering forum strikes again.

It's been kind of slow loading lately. I suspect the browser makes repeated attempts to load when the source server times out, resulting in multiple posts.

Randall, I don't have the heavy duty heat source here in the city you are looking for but I do have the engine that David delivered to deer camp for you.
David said he'd try to send it via WayneFreight, but I hadn't heard anything for a while. Thanks for carting it. I'll shoot you an email to arrange pickup.

Speaking of deer camp, my brother-in-law does have an acetylene tourch 150 miles away in Wisconsin which you could use. I will be driving up there sometime this weekend to winterize my place.
Unless you have a heavy vice at the cabin, I think it would be difficult to do up there. That's why I'm looking for a potable rig, so we can do the bending on my bench.

Plus, my weekend is already pretty full, as it is. My wife likes to pick up extra hours whenever I have time off, and the 1-1/2 year old (nicknamed Curious Georgette) needs constant supervision/rescue. Her older sisters will provide that for all of 3 seconds. (So why don't I get anything done around the house?)

I don't remember how to use the torch but if you know how to, you may.
I'm hoping to borrow some expertise, too. I've only used my brother's a couple times, and I have about enough skill to burn down the garage.

I just had a thought -- maybe I could rent a portable rig. If I can, does anyone without a torch want to come play with fire? (I'll need a few guys to form the bucket brigade when the garage goes up.) It won't be this weekend. Next is probably out, too. Hmm... it'll probably be spring before it happens, after all. I'll let y'all know if I find a opportunity.

By the way, Wayne, how was the opener?

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I don't know if heat would be the best idea or not,,,the bend in the rail is a long gradual bend. If you heat it it will bend where it is heated,,even if you heat the whole rail until it is cherry red, it will bend where you pull from. This probably will not put the steering stem back into place, you will probably have to heat the stem and try to get it straight.

Another problem you may have is that if you get it hot enough to bend, it may deform the rail where you apply the pull.
The right-side tube of the triple spine is clearly bent in one spot. My plan is to heat it there, and heat the center spine closer to the steering head tube (not where my prybar will contact.) The main tube is twisted, rather than bent, and I want it to untwist below the head tube mountings, so as not to jeopardize the welds in that area. I'd like to avoid prying inside the head tube, but if straightening the right-side tube isn't enough, I'll try it. The correct size pipe in the head tube, and enough heat in the right place on the center spine should let me twist it without deforming the head tube. And I think the secondary spines will tend to align the main spine enough that it won't be distorted.

You would need some kind of half tube shape to fit over the rail so it would not deform or flatten the rail.
That's a great idea! You're correct that the lever will need to contact the right-side spine right where the heat will be applied. I can cut a short section of iron pipe in half to cradle that tube.

I think a hydraulic ram may be a better option.
The closest I can get to that would be pressing the bent right spine in the wide jaws of my vice. But heated, it would tend to flatten the tube. I've straightened lots of things that way without heat, but none of them were this heavy or needed to be this precise.

I'll give it a try, and if it doesn't work out, I'll just have to find another frame (maybe with a title, too, and save that headache.)

The frame David had was from a 650 (CX or GL, I don't remember.) Otherwise, I'd have driven to Appleton to buy him a pizza.
(If he hasn't taken you to Stuc's, you've really missed out.)

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I've never have used heat bending frames.

I do use "come a longs" Pipe wrenches, and long persuaders... Lot's of gentle small increments with the frame in a jig (vise
) On a frame with this much distortion, I'd take it to a Racer/Fabricator friend here and have him do it on his frame table.

Eyeballing the head angle is something I would not do as the effect of a twist here can increase geometrically at speed... going from a slight wobble to a big shimmy real fast. I just would never feel confident in my "Eye" nor the bike.

IF the welds crack, they were probably already cracked or on their way to being cracked
and at least you can Re-weld them. High Carbon steel will become weak around the weld if too much heat is applied. You could destroy the frame real quick using a torch.

My .02 HTH

Reading Material...
Thanks for the frame-building link, Jeff. It was an informative read.

It seems I haven't considered the annealing affect of heating the frame. I had assumed with mild steel it wouldn't produce much of a change beyond removing any work-hardening introduced during the crash. Before I go the torch route, I'll try working it cold.

I won't be eyeballing anything. As I did in my initial examination, I'll be comparing a level placed on the rear engine mounting bolt to a lever placed across the end of the head tube. Even if it's a little off in between, this should keep all the running gear in alignment. I won't be able to check actual wheel alignment until I've completed some initial assembly.

Thanks, all, for your input. You've likely saved my some headaches.

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Before I go the torch route, I'll try working it cold.
Well, I made the attempt yesterday, and I only succeeded at scratching the paint.

Now, I'm thinking about sourcing another frame. Jwnovaman offered one back in the spring. Even if it's still available, shipping will likely be a deal-buster. I'll get the swingarm off and weight the frame to calculate the actual cost.

Before finding a replacement, I really should resolve the rear suspension question. Extended shocks for a CX frame would probably be cheaper and easier to source than the appropriate mono-shock.

If I can rent a torch kit, maybe "I'll give it a shot that way before I abandon the frame I have. If that doesn't work, I'll use it for experimenting before it gets recycled.


P.S. My 1-1/2 year old is sitting on my lap. She points at my Red Stig avatar and says "Dada!"
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Did you hone the cylinders yet? Is the block good enough to use in your project? The rust in the cylinders is basically surface rust from sitting outside.
Thanks again for the box of parts, David. Wayne dropped them off Saturday morning. I haven't had time for more than a glance as I repacked them in a sealed bin. I got the hone from Phil, but I've only used it on the forensics project, so far.

another great idea... I forgot the "bottle" jack. works like a champ.... But I would not wedge it under a beam or header in a wooden building unless I wanted to raise the roof or level the floors
There's no room for a bottle jack, but I did check the sissor jacks in my cars. Neither is slim enough. Starting out, I've only got about 1-1/2" between the tubes. It's too bad I don't have the old barn jacks from the farm.

I posted an ad on Craigslist this morning, looking for someone who can straighten a frame. We'll see if I get any response.

I posted an ad on Craigslist this morning, looking for someone who can straighten a frame. We'll see if I get any response.
Wow! Four replies in the first six hours.
Now I have a few leads to pursue.

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You put motorcycle frame right?
And I posted in the Motorcycles For Sale section.

Great! Let us know what you end up doing. I may check out a couple of shops locally myself and see what it'll cost if I decide to go the same route. But then again, I am cheap and besides, figuring out how to do it myself and trying it out is most of the fun!
I've talked to a couple shops. The one that still does frames estimated $300 to $600. I could buy another whole bike for that.

Still need to contact some others I was referred to, but it doesn't look promising.

Does anyone have experience with MAPP gas, or whatever is passed off as MAPP these days? Would it generate enough heat to allow me to bend the steel frame?

It would probably be safer than acetylene for a novice like me. It should be within my budget to buy a MAPP torch. And I've considered getting one for brazing, anyway, but I'd like to know if it would work on the frame before buying.


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Beware, once you get into oxy/gas you start pricing electric welding.
I'll be replacing the electric line to my garage in the Spring, and I hope to run a 50A circuit with a sub-panel in the garage so I can power a basic stick welder.

Just had a thought, maybe I should run 240V out there. Have to study that option.


I've done that on my past two garages. It's nice to have CURRENT capacity to the garage. Sucks when you trip a 120v single breaker and have to walk back to the panel and reset it...more than once! BT,DT...
That's the reason for wanting the sub-panel, so I don't have to trudge through the house in my dirty boots.

The only time I've ever tripped the garage circuit, aside from the underground short that's prompting the replacement, was while vacuuming out the car. Of course, I don't have the welder, yet.

Randall, don't forget the conversation we had on Saturday... We agreed then that you need a new two story garage. And I happen to know the contractor who could build it for ya!
I'd be happy just to have frost footings and a monolithic floor.

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Don't forget that David in Wisconsin has a cx650 frame with title that I'm suppose to pick up but if you want it I'm sure we can find a way to get it to you. Even if it means trailering it to the twin cities ride.
Thanks, Don. It's tempting, but if I have a 650 frame, I'll end up wanting a 650 engine to go in it. That's a slippery slope I don't want to go near.

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The first response to my CL ad pointed me to something called "flame straightening." I did a little digging, and it looks like something I might be able to handle.

It involves pre-tensioning the bent member toward its original position, and heating it to an orange glow to relieve the internal stresses in the material. The idea is that the heated metal will expand in every direction, except that in which it is constrained by the pretensioning, but when it cools, it will shrink in all directions. Repeating the procedure will eventually change the piece into the desired shape.

There has been some concern expressed of weakening the steel. A couple of the references I found say that this process is no more detrimental to mild steel than welding, and may even result in a stronger piece, due to equalizing the internal stresses left by initial shaping.

For the bent secondary spine tube, I'll pre-tension the tube on each side of the bend using either wooden wedges or the screw from a c-clamp. If I brace the body of the clamp against the primary tube and set the swivel foot against the secondary, I should be able to use the screw as a spreader.

For whatever twist remains in the steering stem tube, I'll need to bolt the frame down on its side to the workbench (unless it's secure enough in the vise) and use a combination of the floor jack on the bench and a weight over the floor at either end of a pipe through the stem. I should be able to generate sufficient heat using a large head on the LP torch.

Now if I can get some warm Saturdays with time to waste, I'll be able to try this.

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